Open up this master folder in MS Code.
Only edit the /src/index.js to make code changes.
Open terminal with Ctrl + ~.
In first terminal, type "npm install" to get all the needed packages.
In first terminal, type "npx webpack" to have webpack compile the /dist/main.js from the /src/index.js. It will automatically recompile every time you save changes to /src/index.js and other code files.
Add another terminal with the plus sign button.
In second terminal, "cd dist" to change to the /dist folder.
Type "http-server" to start up a web server from that /dist folder.
Click on the 127.0.0.1:8080 or type that URL in your browser (tested OK in Chrome).
Click the start button, it should ask permission to use the microphone. Click Yes/Allow.
Say something. Click the stop button. It should immediately play back your voice but 7 semitones lower.